They are enclosed in permeable bags or pouches (1) which enable them to swell as they absorb water by spraying and to return it, after having been placed at the bottom of the pot (9), as it is required by the plant and to do so in a way which is clean and quick for the user to operate. The packaging of the said hydroretainers in the bags or pouches (1), in which they are free, enables them to inflate to the maximum, whence a maximum efficiency of their water-retention capacity. The structure of the bag or pouch (1) is such that it is permeable to water but impermeable to crystals of products (2); moreover, the structure of the bag (1) can permit roots to enter into the bag (1) and to come into direct contact with the hydroretention product (2). Hydroretainers particularly for indoor plants. <IMAGE>
